Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates generally to user-actuated control of apparatus. More particularly, the present invention relates to proportional control of rotary and/or linear actuators by body-component-actuated transducers.
2. Description of the Related Art
Control of linear and rotary actuators often includes the requirement that rotational speeds of rotary actuators or linear velocities of linear actuators be precisely controlled.
For instance, when both the speed and steering of a vehicle are controlled by controlling speeds and rotational directions of a pair of electric motors, it is important to separately and precisely control their rotational speeds and differences between their rotational speeds.
Conveyances, or electrically-propelled wheelchairs, provide mobility for a multitude of persons ranging in age from children less than three years old who will never walk, to adults who have been injured in accidents or afflicted with a debilitating illness to elderly people who have acquired infirmities as they have aged.
To these people, their freedom of mobility, and to a large extent their ability to be productive citizens in society, depend upon the mobility afforded by a power wheelchair. Included in this large group of people are some who lack either the use of limb or the motor skills to use the kinds of controls common on power wheelchairs.
Typically, power wheelchairs have been propelled by separate electric motors drivingly connected to left and right wheels of the wheelchair.
By controlling both the equivalent voltage and polarity to the motors, control of forward and reverse directions, speeds, and steering have been controlled. This control of steering includes turns in which the wheelchair pivots around one wheel, and pivot turns in which the wheels rotate in opposite directions at the same or unequal speeds.
Typical control of electrically-propelled wheelchairs has been by an X-Y input device in which a joystick is manually positioned with respect to X and Y axes to selectively provide mechanical inputs to transducers.
While some degree of control can be achieved by simple on-off and forward-reverse control of the driving wheel motors, and while a severely handicapped person may be grateful for the freedom and the personal achievement, on-off controls severely limit the speed, maneuverability, and controllability of the wheelchair.
Perhaps more importantly, this type of simplistic control fails in an area that can be more important to a handicapped person. By failing to allow him to control speeds and steering proportionally, it fails to allow him to use his full physical and mental capabilities.
A problem in achieving satisfactory control of a wheelchair by joystick control has been hand tremors of the user. Lautzenhiser et al., in U.S. Pat. No. 5,012,165, solves the problem of hand tremors by integrating signal variations caused by hand tremors, thereby providing an integrated, or averaged, output.
Even for those with good dexterity with at least one hand, skillful control of power wheelchairs by X-Y input devices has not been as easy as would be desired. It has been difficult, even for those with good motor skills, to drive in a straight path and to make minor changes in direction without overcorrecting.
Included in attempts to overcome this steering problem, is Klimo, U.S. Pat. No. 4,634,941, who has provided a diamond-shaped guide to help the user find the joystick position that results in driving a straight path.
Bell, in U.S. Pat. No. 4,667,136, attempted to overcome this steering problem by placing a resistor between the outputs of two potentiometers, to reduce the differences between the two electrical signals, and thereby to reduce steering sensitivity.
While Bell""s use of a resistor does achieve a decrease in steering sensitivity, it is important to notice that the decrease in differences between the electrical signals produced by the two potentiometers is linear. That is, a small difference in electrical signals produces a small decrease in the difference between the electrical signals, and larger differences result in proportionally larger decreases in the differences.
When differences between the electrical signals are small, such as when attempting to steer a straight path, a large percentage decrease in the differences in the electrical signals is needed to effectively reduce steering sensitivity, but Bell""s resistor provides a relatively small, and therefore insufficient, reduction in the differences between the two electrical signals unless the resistance of Bell""s resistor is relatively small.
However, when attempting to make a sharp turn or a pivot turn, and the differences between the electrical signals are large, a relatively low resistance makes a large decrease in the differences in the electrical signals, thereby decreasing steering sensitivity so severely that it is impossible to effect sharp turns and pivot turns.
Therefore, the use of any fixed resistance that adequately reduces sensitivity for steering a straight path, so severely reduces the difference between the two electrical signals when differences between the signals are large that it is impossible to make sharp turns or pivot turns.
Lautzenhiser, in U.S. Pat. No. 5,635,807 solves the problem of difficult steering control. Instead of allowing the high-side signal to be reduced by flowing through a resistor to the low-side, as taught by Bell, differences in the two control signals are reduced as an inverse, nonlinear, and steady-state function of the differences in the two control signals.
Prior to the teaching of Lautzenhiser as discussed in the preceding paragraph, not only has manual control of a joystick been difficult for many handicapped persons, it has been impossible for others. For those lacking the physical capability of using a joystick, various devices have been proposed.
Witney et al., in U.S. Pat. No. 4,323,829, disclose a xe2x80x9cwaffle boardxe2x80x9d control. In use, pressing fingers on selective portions of the horizontally-disposed xe2x80x9cwaffle boardxe2x80x9d provides control of speed and steering of a wheelchair.
Others have proposed controls that are actuated by body components other than a hand of the user. Glaser et al., in U.S. Pat. No. 4,523,769, teach a wheelchair in which the feet are used to achieve control of speeds and steering of a wheelchair. The footrests are moveable to positions wherein drive pawls are engaged, providing on-off control of the speeds of each motor.
Mogle, in U.S. Pat. No. 3,965,402, teaches a headrest proportional control. Although his device appears to be tedious to use because of constriction of the user by the headrest control, it seems to advance the art to some degree. Miller, III, in U.S. Pat. No. 4,093,037, also teaches a headrest control for wheelchairs.
Brown et al., in U.S. Pat. No. 4,078,627, teach a chin rest, and control of a wheelchair by chin movement. This device appears to be even more constrictive than those of Mogle and Miller, III.
A still more constrictive device is the xe2x80x9csip and puffxe2x80x9d device taught by Muller in U.S. Pat. No. 4,865,610. In addition, it is highly impractical for those who depend upon a ventilator for breathing.
Loveless et al., in U.S. Pat. No. 4,260,035, teach chin control in which the transducers may be mechanical or optical, with the optical device being somewhat less constrictive. Fetchko, in U.S. Pat. No. 4,486,630, teaches a device in which the user wears a rather complex and cumbersome headset, and control of various devices is achieved by moving the user""s jaw or eyebrows.
Johnston, U.S. Pat. No. 4,281,734, frees the user of the cumbersome headset of Fetchko by teaching the use of light sensors that are attached behind the head of the user. Simmons et al., in U.S. Pat. No. 3,993,154, seem to advance the art by teaching apparatus in which an energy field is directed toward the user""s body, and a field pickup element senses changes in positioning of the user""s head.
Crawford, Jr., in U.S. Pat. No. 4,158,196, teaches sensing of bioelectric signals by electrodes that may be attached to, or implanted into, a user""s skull. Youdin et al., in U.S. Pat. No. 4,207,959, teach a voice-actuated control in which incremental changes in speed and steering may be achieved.
Selwyn, U.S. Pat. No. 3,374,845, teaches the use of a helmet that includes a plurality of on-off switches that are selectively activated by the user tilting his head along a selective one of a plurality of sensing axes. While he provides improved freedom of movement for the user, he fails to provide proportional control of speeds and steering, thereby severely limiting both the controllability and the maximum safe speed of operation.
Kelly et al., in U.S. Pat. No. 4,866,850, teach the use of a conductive-ball wiped potentiometer as a sensor for a digital-readout clinometer. The ball, which they say may be solid or liquid, is gravity positioned with respect to a circular resistance element. Mercury is mentioned as one choice for the ball.
While gravity-actuation of head mounted transducers, or body-component mounted transducers, would provide more freedom for the user than backrest and chin rest actuated transducers, their limitation to on-off control of wheelchair functions, such as taught by Selwyn, falls far short of being desirable.
While on-off control of speed and steering of a wheelchair by the use of gravity-actuated switches, such as taught by Selwyn, is easily achievable, attempting to achieve proportional control of the wheel motors, or other actuators, by gravity-actuated proportional-output transducers has been fraught with difficulties.
That is, the outputs of some gravity-actuated proportional-output transducers are subject to excessive and wild excursions. Further, because of the high specific gravity of mercury, it is doubtful that there is any other gravity-actuated transducer in which the electrical output is more subject to wild and undamped excursions.
Therefore, while the use of gravity-actuated and mercury-wiped transducers for controlling wheelchairs has been an interesting thought, because of the erratic electrical output, except for on-off control, the uses of these transducers have been limited to digital readout devices in which the transducer output has been time-averaged to produce viable results.
Those who cannot use a joystick need a control that is easier to use and that provides better control than a xe2x80x9cwaffle boardxe2x80x9d Even those who are not on a ventilator need a system that is easier to control than a xe2x80x9csip and puffxe2x80x9d system. Handicapped persons need more freedom of movement than that provided by a headrest or chin rest system. They need a better control than the on-off head-actuated control of Selwyn.
They need a proportional output system with head-attached, or body-component-attached, proportional-output transducers. And to make this system easy to use, even for those who have poor coordination, they need both the inverse nonlinearity and the personalized sensitivity adjustments as taught in the present patent application and in the patent upon which the present application depends.
The present invention provides proportional control of actuators, whether electric, or hydraulic, or pneumatic, and whether rotary or linear. This proportional control of actuators includes proportional control of the rotational speed of rotary actuators and proportional control of the velocity of linear actuators.
In the present invention, proportional control is achieved by the use of body-component-attached transducers, or transducers of any type that are actuated by any means, even by a gyroscopic device. However, preferably, gravity-actuated sensors, or tilt-axis input devices are used.
If tilt-axis transducers are used, a tilt-axis X-Y input device is head attached, or attached to some other body-component. Tilting of the user""s head along a tilt axis to various tilt angles produces electrical outputs that are proportional to the tilt angles. The electrical outputs of the transducers are conditioned to overcome head or other body-component tremors, to selectively decrease the tilt-angle sensitivity of the transducers, and/or to selectively decrease sensitivity of one transducer with respect to an output of another transducer.
The conditioned output is used to achieve proportional control of a single actuator, a plurality of actuators, an augmentative device, a robotics device, or a conveyance for handicapped persons.
As taught herein, the electrical outputs of the transducers may be conditioned by analog circuitry or by digital conversion in a microprocessor.
However, whether conditioning of the electrical outputs of the transducers is by analog circuitry or digital conversion, as taught herein, selectable adjustment of proportionality may be provided for the convenience of the user, caregiver, or therapist.
The signal conditioning of the present invention includes limiting the rate of change of the electrical output of a single transducer, limiting the rate of change in differences in the electrical outputs of two transducers, selectively changing the proportionality of tilt angle to electrical output, and changing the electrical output of one transducer as an inverse and linear or nonlinear function.
This changing of an electrical output of a transducer as an inverse and linear or nonlinear function includes changing the electrical output as a function of the electrical output of another transducer, or as a function of the difference in the electrical outputs of two transducers.
As described in detail herein, the present invention provides body-component-attached transducers and signal conditioning apparatus for controlling computer cursers, for achieving proportional or non-proportional control of an actuator, for controlling augmentative devices, for controlling robotics devices, and for controlling both the speed and steering of an electrically-propelled conveyance of the kind in which the speed and steering are controlled by speeds and relative speeds of first and second electric motors.
If, for example, two transducers are attached to the head of a user, tilting of the user""s head with respect to X and Y axes will provide electrical outputs that are used to control both speeds and relative speeds of the electric motors.
If first electrical outputs of a,first transducer are used to control the speeds of both motors, and second electrical outputs of a second transducer are used to control differences in motor speeds, then the steering sensitivity control of the present invention decreases the magnitude of one of the electrical outputs as an inverse and linear or nonlinear function of the other electrical outputs.
However, if the transducers are oriented so that the electrical outputs of both transducers are used to control the speeds of both motors, and differences in the electrical outputs are used to control steering, then the sensitivity control of the present invention decreases the difference in the electrical outputs as an inverse and nonlinear function of differences in the electrical outputs of the two motors.
One advantage of the steering sensitivity control is greatly enhanced ease of steering. This ease of steering makes head-actuated controls not only feasible, but also very practical.
In addition, the inverse linear or nonlinear conditioning of the transducer outputs adds to the practicality of using head-attached transducers.
The present invention also provides selective adjustment of transducer sensitivity. When joystick-actuated potentiometers are used for transducers, the transducer sensitivity control selectively adjusts the voltage change per angle of inclination of the joystick, or body-component-attached transducer.
When body-component-attached tilt transducers, or tilt-axis X-Y input devices are used, the transducer sensitivity control taught herein selectively adjusts the voltage change per degree of tilt angle of the transducers.
The present invention also provides adjustable speed limiting while allowing mechanical inputs to the X-Y input device to greatly exceed inputs that would ordinarily produce excessive speeds of the motors.
Finally, the apparatus of the present invention preferably includes circuity for bringing the conveyance to a stop if an attached body-component electronic device is actuated beyond its normal range. This provision stops the conveyance in instances in which the occupant/operator has a seizure, faints, or otherwise suffers a sudden physical, mental or emotional condition that results in a sudden maximum speed signal.
In a first aspect of the present invention, a method for controlling rotational speeds of first and second motors comprises: selectively inputting X and Y transducers; producing X and Y electrical outputs separately proportional to the selective inputting step; proportioning one of the electrical outputs as an inverse function of an other of, the electrical outputs; and rotating one of the electrical motors as a function of the proportioning step.
In a second aspect of the present invention, a method for controlling both speeds and steering of a conveyance comprises: body-component attaching first and second tilt-angle transducers; body-component actuating the transducers to selected tilt angles; producing a first electrical output from the first transducer proportional to the selected tilt angles with respect to a one tilt axis; producing a second electrical output from the second transducer proportional to the selected tilt angles with respect to an other tilt axis; conditioning the first electrical output as an inverse function of the second electrical output; and controlling rotational directions and rotational speeds of first and second motors as a function of the producing and conditioning steps.
In a third aspect of the present invention, apparatus for controlling rotational speeds of first and second motors that are connected to respective ones of left and right wheels comprises: means for producing a first electrical output proportional to a first mechanical input; means for producing a second electrical output proportional to a second mechanical input; and means, being operatively connected to the first and second electrical outputs, for inverse proportioning the first electrical output as a function of one of the second electrical output.